Validation of a Password - Python

Question

So I have to create code that validate whether a password:

• Is at least 8 characters long
• Contains at least 1 number
• Contains at least 1

Answer 1

Python 2.7 The for loop will assign a condition number for each character. i.e. Pa$$w0rd in a list would = 1,2,4,4,2,3,2,2,5. Since sets only contains unique values, the set would = 1,2,3,4,5; therefore since all conditions are met the len of the set would = 5. if it was pa$$w the set would = 2,4 and len would = 2 therefore invalid

name = raw_input("Enter a Password: ")
list_pass=set()
special_char=['#','$','@']
for i in name:
    if(i.isupper()):
      list_pass.add('1')
  elif (i.islower()):
      list_pass.add('2')
  elif(i.isdigit()) :
      list_pass.add('3')
  elif(i in special_char):
      list_pass.add('4')
if len(name) >=6 and len(name) <=12:
    list_pass.add('5')
if len(list_pass) is 5:
    print ("Password valid")
else: print("Password invalid")

Answer 2

You can use re module for regular expressions.

With it your code would look like this:

import re

def validate():
    while True:
        password = raw_input("Enter a password: ")
        if len(password) < 8:
            print("Make sure your password is at lest 8 letters")
        elif re.search('[0-9]',password) is None:
            print("Make sure your password has a number in it")
        elif re.search('[A-Z]',password) is None: 
            print("Make sure your password has a capital letter in it")
        else:
            print("Your password seems fine")
            break

validate()

Answer 3

r_p = re.compile('^(?=\S{6,20}$)(?=.*?\d)(?=.*?[a-z])(?=.*?[A-Z])(?=.*?[^A-Za-z\s0-9])')

this code will validate your password with :

1. min length is 6 and max length is 20
2. at least include a digit number,
3. at least a upcase and a lowcase letter
4. at least a special characters

Answer 4

You are checking isdigit and isupper methods on the entire password string object not on each character of the string. The following is a function which checks if the password meets your specific requirements. It does not use any regex stuff. It also prints all the defects of the entered password.

#!/usr/bin/python3
def passwd_check(passwd):
    """Check if the password is valid.

    This function checks the following conditions
    if its length is greater than 6 and less than 8
    if it has at least one uppercase letter
    if it has at least one lowercase letter
    if it has at least one numeral
    if it has any of the required special symbols
    """
    SpecialSym=['$','@','#']
    return_val=True
    if len(passwd) < 6:
        print('the length of password should be at least 6 char long')
        return_val=False
    if len(passwd) > 8:
        print('the length of password should be not be greater than 8')
        return_val=False
    if not any(char.isdigit() for char in passwd):
        print('the password should have at least one numeral')
        return_val=False
    if not any(char.isupper() for char in passwd):
        print('the password should have at least one uppercase letter')
        return_val=False
    if not any(char.islower() for char in passwd):
        print('the password should have at least one lowercase letter')
        return_val=False
    if not any(char in SpecialSym for char in passwd):
        print('the password should have at least one of the symbols $@#')
        return_val=False
    if return_val:
        print('Ok')
    return return_val

print(passwd_check.__doc__)
passwd = input('enter the password : ')
print(passwd_check(passwd))

Answer 5

• isdigit() checks the whole string is a digit, not if the string contains a digit

  Return true if all characters in the string are digits and there is at least one character, false otherwise.

• isupper() checks the whole string is in uppercase, not if the string contains at least one uppercase character.

  Return true if all cased characters in the string are uppercase and there is at least one cased character, false otherwise.

What you need is using the any built-in function:

• any([x.isdigit() for x in password]) will return True if at least one digit is present in password
• any([x.isupper() for x in password]) will return True if at least one character is considered as uppercase.

Answer 6

Example:

class Password:
    def __init__(self, password):
        self.password = password

    def validate(self):        
        vals = {
        'Password must contain an uppercase letter.': lambda s: any(x.isupper() for x in s),
        'Password must contain a lowercase letter.': lambda s: any(x.islower() for x in s),
        'Password must contain a digit.': lambda s: any(x.isdigit() for x in s),
        'Password must be at least 8 characters.': lambda s: len(s) >= 8,
        'Password cannot contain white spaces.': lambda s: not any(x.isspace() for x in s)            
        } 
        valid = True  
        for n, val in vals.items():                         
           if not val(self.password):                   
               valid = False
               return n
        return valid                

    def compare(self, password2):
        if self.password == password2:
            return True


if __name__ == '__main__':
    input_password = input('Insert Password: ')
    input_password2 = input('Repeat Password: ')
    p = Password(input_password)
    if p.validate() is True:
        if p.compare(input_password2) is True:
            print('OK')
    else:
       print(p.validate())